BACKGROUND: The severity and complications of type 2 diabetes mellitus (T2DM) are the most important preventable health burdens. This study was undertaken to assess the impact of hyperglycemia on hematological indices in patients with T2DM. MATERIALS AND METHODS: This study was conducted on 300 patients with T2DM, which included group A having controlled diabetes [hemoglobin A1c (HbA1c) <
7%] and group B having uncontrolled diabetes (HbA1c >
7%). Information concerning medical history, physical examination, diabetic parameters, hematological indices, and laboratory findings was extracted for interpretation and association between both groups. RESULTS: About 115 patients (38.33%) had HbA1c <
7% and 185 patients (61.67%) had HbA1c >
7%. Total leukocyte count (TLC), monocytes, basophils, red cell distribution width (RDW-CV), platelet distribution width (PDW), mean platelet volume (MPV), platelet large cell ratio (P-LCR), plateletcrit (PCT), neutrophil-to-lymphocyte ratio (NLR), and platelet-to-lymphocyte ratio (PLR) were significantly higher among patients with uncontrolled T2DM compared to those with controlled T2DM ( CONCLUSION: This study concluded that inflammation, tendency to coagulation, and thrombosis can be detected with easily accessible and inexpensive hematological indices. Therefore, hematological indices can be used as a direct measure to detect the severity of T2DM and its complications.